Printing a singly linked list using classes - class

Question

I am making a program for singly linked lists using multiple files and classes.
I have to have a Node.h, LinkedList.h, Node.cpp, LinkedList.cpp, and a main.cpp
I was having other problems but now my printList() function just prints "List()" instead of "List(node 1, node2, etc...)"
I think my insert might be the problem because my searchNode() doesn't work right either, it always says node not found.
Here is the code I have: (I can't change the Node.h and LinkedList.h files)
Node.h:
//
// Node.h
// Linked Lists
//
#ifndef Linked_Lists_Node_h
#define Linked_Lists_Node_h
class Node
{
public:
Node(int data);
int data;
Node *next;
};
#endif
LinkedList.h:
//
// LinkedList.h
// Linked Lists
//
#ifndef Linked_Lists_LinkedList_h
#define Linked_Lists_LinkedList_h
#include "Node.h"
class LinkedList
{
private:
Node *head;
public:
LinkedList();
void addNode(int data);
void removeNode(int data);
bool searchNode(int data);
void printList();
};
#endif
Node.cpp
//
// Node.cpp
// Linked Lists
//
#include <iostream>
#include <cstdlib>
#include "LinkedList.h"
#include "Node.h"
using namespace std;
Node::Node(int data) {};
LinkedList.cpp
//
// LinkedList.cpp
// Linked Lists
//
#include <iostream>
#include <cstdlib>
#include "LinkedList.h"
#include "Node.h"
using namespace std;
LinkedList::LinkedList()
{
head = NULL;
}
void LinkedList::addNode(int data)
{
Node *newNode;
newNode->data = data;
newNode->next = NULL;
Node *tmp = head;
if(tmp != NULL)
{
while(tmp->next != NULL)
{
tmp = tmp->next;
}
tmp->next = newNode;
}
cout << "Node added" << endl;
printList();
}
void LinkedList::removeNode(int data)
{
Node *tmp = head;
if(tmp == NULL)
{
cout << "No node removed" << endl;
return;
}
if(tmp->next == NULL)
{
delete tmp;
head = NULL;
}
else
{
Node *previous;
do
{
if(tmp->data == data)
{
break;
}
previous = tmp;
tmp = tmp->next;
}
while(tmp != NULL);
previous->next = tmp->next;
delete tmp;
}
cout << "Node removed" << endl;
printList();
}
bool LinkedList::searchNode(int data)
{
Node *tmp = head;
while(tmp != NULL)
{
if(tmp->data == data)
{
cout << "Node found" << endl;
printList();
return true;
}
tmp = tmp->next;
}
cout << "Node not found" << endl;
printList();
return false;
}
void LinkedList::printList()
{
Node *tmp = head;
if(tmp == NULL)
{
cout << "List()" << endl;
return;
}
if(tmp->next == NULL)
{
cout << "List(" << tmp->data << ")";
}
else
{
do
{
cout << "List(" << tmp->data;
cout << ", ";
tmp = tmp->next;
}
while (tmp != NULL);
cout << ")" << endl;
}
}
main.cpp
//
// main.cpp
// Linked Lists
//
#include <iostream>
#include <cstdlib>
#include "LinkedList.h"
#include "Node.h"
#include "LinkedList.cpp"
using namespace std;
int main ()
{
LinkedList list;
int data;
int choice;
while(1)
{
cout << " Select:" << endl;
cout << "1 to add a node" <<endl;
cout << "2 to remove a node" << endl;
cout << "3 to search for a node" << endl;
cout << "4 to exit" << endl;
cout << endl;
cin >> choice;
switch(choice)
{
case 1: //insertion
cout << "Enter node: ";
cin >> data;
list.addNode(data); //add a node
break;
case 2: //deletion
cout << "Enter node: ";
cin >> data;
list.removeNode(data); //remove a node
break;
case 3: //search
cout << "Enter node: ";
cin >> data;
list.searchNode(data); //search for a node
break;
case 4:
exit(0); //exit the program
break;
default: //default case
cout << "Please enter a valid choice (1 - 4)!" << endl;
break;
}
}
return 0;
}
If you could help me figure out my problem I would greatly appreciate it.

Answer 1

You're not adding any nodes. If head is NULL, your add Node becomes:
void LinkedList::addNode(int data)
{
Node *newNode;
newNode->data = data;
newNode->next = NULL;
Node *tmp = head;
if(tmp != NULL)
{
//this never gets executed
}
cout << "Node added" << endl;
printList();
}
You need to treat this case (first insertion):
void LinkedList::addNode(int data)
{
Node *newNode;
newNode->data = data;
newNode->next = NULL;
Node *tmp = head;
if(tmp != NULL)
{
while(tmp->next != NULL)
{
tmp = tmp->next;
}
tmp->next = newNode;
}
else
{
head = newNode;
}
cout << "Node added" << endl;
printList();
}
This will create the head if it doesn't exist already.
Are you using a debugger? It would be much easier (for you) if you did.